Heretofore multifilament polyester fibrous materials have achieved widescale acceptance as a fibrous reinforcing medium when incorporated in a rubber matrix of vehicle (e.g. automobile) tires. For instance, polyethylene terephthalate tire cords are recognized to impart smoother ride characteristics when compared to rubber tires which incorporate nylon tire cords and which have a tendency at least initially to produce pavement pounding particularly in cold weather.
Customarily a conventional fiber finish and a conventional adhesive are applied to the multifilament fibrous materials prior to incorporation in the rubber tire matrix.
It has been recognized, however, that polyester tire cords have a tendency to be adversely influenced by heat during extended use and to exhibit a substantial drop in strength retention. Accordingly, rubber tires which incorporate polyester tire cords have been used almost exclusively on automobiles, and have been largely avoided for use on heavy duty trucks.
It is an object of the present invention to provide improved polyester fibers for use as a reinforcing medium in rubber tires.
It is an object of the present invention to provide improved polyester fibers which exhibit enhanced chemical stability when incorporated in a rubber matrix at an elevated temperature.
It is an object of the present invention to provide improved polyester fibers for incorporation in rubber tires which offer a greater margin of safety under severe operating conditions (e.g. highly elevated operating temperatures).
It is another object of the present invention to provide a simple and inexpensive treatment process for polyester fibers intended for incorporation in rubber tires which is capable of decreasing the degradation of the same under use conditions.
It is a further object of the present invention to provide a process for the treatment of polyester fibers for use in tires which is capable of extending the useful life of the same during tire use.
These and other objects of the invention will be apparent to those skilled in the art from the following description.